Heterocyclic derivatives of steroids have emerged as promising anticancer agents by concurrently targeting multiple pathways, including apoptosis induction, cell cycle arrest, and mitochondrial dysfunction. Here, we report novel pregnenolone-isoxazole hybrids as selective anticancer agents targeting mitochondrial apoptosis. Starting from 20-vinyl pregnenes, nitroisoxazole-substituted pregnenolone derivatives were synthesized and subjected to nucleophilic aromatic substitution, yielding a variety of pregnenolone-isoxazole hybrids bearing azido, phenylthio, and amino groups. In total, 33 new compounds were prepared and evaluated for their in vitro antiproliferative activity against breast cancer cells. The lead compound, 20-[3'-(5″-nitro)isoxazole]-pregna-5-ene-3β-ol-20-one, demonstrated IC50 values of 2.8 μM or lower against MCF7, MCF7/HT2, MDA-MB-231, and HCC1954 breast cancer cell lines under both normoxic and hypoxic conditions. This compound induced mitochondria-dependent apoptosis in MCF7 cells in a concentration-dependent manner. Modulation of key proliferation pathways, including the PI3K/Akt and ERK cascades, further supported the antiproliferative potential of these derivatives. Considering its high cytotoxicity and antiproliferative activity in breast cancer cells, the lead compound has been identified as a promising candidate for further development.

This study focused on the synthesis of secosteroids with good antiproliferative properties against hormone-dependent breast cancer. A straightforward and efficient method for synthesizing secosteroid - 1,3,4-oxadiazole hybrids was developed starting from 13α-hydroxy-3-methoxy-13,17-secoestra-1,3,5(10)-trien-17-oic acid hydrazide. The cyclization of hydrazide moiety with CS2 into 1,3,4-oxadiazole-2(3H)-thione fragment followed by sulfur alkylation resulted in the formation of various secosteroid - 2-mercapto-1,3,4-oxadiazole hybrids. These novel compounds were evaluated for their antiproliferative activity against the hormone-dependent human breast cancer cell line MCF-7. Among the synthesized hybrids, compounds 3i, 3o, and 3q displayed notable antiproliferative effects, with IC50 values ranging from 6.5 to 8.9 µM, comparable to the reference drug cisplatin. Furthermore, compound 3i showed minimal toxicity toward non-cancerous hFB-hTERT fibroblasts, indicating high selectivity. Compounds 3o and 3q exhibited antiestrogenic activity. Additionally, their effects on PARP and Bcl-2 suggest a pro-apoptotic mechanism of action. These findings highlight the potential of secosteroidal hybrids as promising candidates for the development of new anti-breast cancer agents targeting ERα and apoptosis pathways.

The aggregation-induced emission (AIE) effect opens up new opportunities and prospects for the development of organic light-emitting materials. By exploiting the intrinsic ability of boron-dipyrromethenes (BODIPYs) to form aggregates, we rationally designed water-soluble AIE-active dyes derived from BODIPY fluorophores by their modification with azamacrocyclic units. The most AIE-active cyclen-BODIPY derivatives 5a and 8a showed high fluorescence quantum yields and they were found to be sensitive to water content, viscosity, pH, and temperature with a "turn-on" fluorescence response. The DLS and SEM results showed that these compounds exist as nanoscale aggregates in aqueous solutions. A possible molecular arrangement of dye 5a in aggregates was rationalized using TD-DFT calculations. The biologically relevant metal ions, such as Li+, K+, Na+, and Mg2+, have no pronounced effect on absorption and emission spectra of the dyes 5a and 8a. In vitro confocal microscopy studies in HeLa cells demonstrated that dyes 5a and 8a successfully permeated the cell membrane and selectively labeled lysosomes. These findings suggest that cyclen-BODIPY derivatives hold promise for investigating lysosomal dynamics and function in living cells via fluorescence imaging.

A method for the synthesis of spiro-1,3,4-thiadiazolines by the reaction of cyclic ketones with oxamic acid thiohydrazides was developed. A number of new nonsteroidal spiro-1,3,4-thiadiazolines was obtained in high yields.

This research aimed to develop novel selective secosteroids that are highly active against hormone-dependent breast cancer. A simple and convenient approach to N '-acylated 13,17-secoestra-1,3,5(10)-trien-17-oic acid hydrazides was disclosed and these novel types of secosteroids were screened for cytotoxicity against the hormonedependent human breast cancer cell line MCF7. Most secosteroid N '-benzoyl hydrazides have demonstrated high cytotoxicity against MCF7 cells with IC50 values below 5 mu M, which are superior to that of the reference drug cisplatin. Hit compounds 2c, 2e and 2i were characterized by high cytotoxicity (IC50 = 1.6-1.9 mu M) and very good selectivity towards MCF7 breast cancer cells. The lead secosteroids 2c, 2e and 2i also exhibit antiestrogenic effects and alter the expression of cell cycle regulating proteins. The effect of selected compounds on PARP (poly (ADP-ribose) polymerase) and Bcl-2 (B-cell CLL/lymphoma 2) indicates their proapoptotic potential. The synthesized secosteroids may be considered as new promising anti-breast cancer agents targeting ER alpha and apoptosis pathways.

This study reports the first general, practical, and facile synthesis of phosphorus-substituted 1,3,4-thiadiazolines starting from phosphorylthioformic acid hydrazides and ketones. Various cyclic ketones were efficiently incorporated into spiro 1,3,4-thiadiazoline derivatives by a two-step sequence involving the heterocyclization with phosphorylthioformic acid hydrazides followed by the nitrogen acylation with acyl chlorides. The protocol is characterized by operational simplicity, readily available reagents, and functional group tolerance.

Estrogen receptor alpha (ERα) is an important target for the discovery of new therapeutic drugs against hormone-dependent breast cancer.

A silver phosphine complex (XantPhos)AgBr proved to be a cheap and readily accessible catalyst for bromofluoro- cyclopropanation of electron-rich alkenes with CFBr2CO2Na. Ozonolysis followed by treatment with NaHSO3 was shown to be an effective protocol to purify gem-bromofluoro- cyclopropanes from unreacted alkene precursors.

A method for the synthesis of 1,3,4-thiadiazoline spiro steroids via ring A by the reaction of steroid 3-ketones with oxamic acid thiohydrazides was developed. It was shown that if a keto group was present both in ring A and in ring D of the precursor steroid, the reaction occurred only at the keto group of ring A. A number of new steroidal 3-spiroandrostene-substituted 1,3,4-thiadiazolines were obtained, which could be easily acetylated at the thiadiazole NH group.

Heterocyclic organophosphorus compounds have remarkable properties and a great deal of potential to meet contemporary societal demands regarding health, environment, energy, and information technologies. Here, we report highly reactive phosphorylthioformic acid hydrazides as novel polyheteroatom reagents for the concise synthesis of phosphorus-substituted medium–ring aza-heterocyclic systems. The reaction of phosphorylthioformic acid hydrazides with functionalized aldehydes was systematically investigated. Chemoselective and flexible synthetic approaches to phosphorus(V)-substituted 1,3,4-thiadiazoles, 1,3,4-thiadiazolines, and pyridazines were developed. Phosphorylthioformic acid hydrazides proved to be useful for the preparation of phosphorus(V)-containing heterocyclic steroid derivatives.

The reaction of hydroxylamine and steroid obtained by the condensation of 16α,17α-epoxypregn-5-en-20-one with DMF dimethyl acetal proceeded through the involvement of the epoxide fragment and led to the formation of 3β-hydroxy-4′-hydroxylaminoandrost-5-eno[16,17-b]pyridine l′-N-oxide.

An effective method for the synthesis of heterocyclic steroids with the [1,2,5]oxadiazolo[3,4-b]pyrazine and [1,2,5]thiadiazolo[3,4-b]-pyrazine fragments was developed. The structure of the products was confirmed by X-ray structural analysis. The resulting compounds showed high antiproliferative activity against breast (MCF7) and prostate (22Rv1) cancer cells, which was not inferior to that of cisplatin and abiraterone acetate.

Starting from 3-methoxyestra-1,3,5(10),16-tetraene-17-carbaldehydes of natural (13β) and epimeric (13α) series, a series of isomeric 3-hydroxy-17-hydroxymethylestra-1,3,5(10)-trienes, including those containing 16α,17α-annulated cyclopropane and cyclohexane ring D', were prepared using the Corey-Chaykovsky and Diels-Alder reactions followed by reduction-demethylation with diisobutylaluminum hydride and hydrogenation. Target compounds showed antiproliferative effects on MCF-7 breast cancer cells to varying degrees superior to that on MCF-10A cells, in low micromolar concentrations. The ERα-mediated luciferase reporter gene assay demonstrated that obtained steroids without an additional carbocycle or with a cyclopropane 16α,17α-annulated carbocycle are effective ERα activators. In this test, steroids of the natural configuration showed high activity at both 10 nM and 100 nM concentrations, whereas 13α-steroids showed a strong dose-dependent effect, surpassing their natural counterparts at a concentration of 100 nM. The 13β-steroid bearing additional 16α,17α-cyclohexane ring had low activity in the test. A simple docking approach using AutoDock Vina was used as a test for a preliminary assessment of the estrogenicity of the compounds. The scope of its applicability and limitations were shown using examples of synthesized molecules.

Data on the influence of solvents, ratios and nature of reagents on the distribution of typical impurities and yields of target products of the reaction of 19-norpregna-1,3,5(10),16-tetraen-20-one derivatives with 4-dimethylamino-, 3,4-dimethoxy-, and 4-bromobenz-aldehydes and 3-pyridinecarbaldehyde were studied and summarized. A mechanism for the formation of 1,3-diketones in the reaction of 17-acetyl-substituted steroids with 4-dimethyl-aminobenzaldehyde in the presence of lithium diisopropylamide in THF was proposed. The Claisen-Schmidt condensation results were shown to be critically affected by the base and the steroid solubility. Optimization possibilities were considered and an improved procedure for the synthesis of new 21-benzylidene-substituted steroids was proposed.

A series of D-ring modified steroids bearing a vinyl ketone pendant were synthesized and evaluated for antiproliferative activity against breast cancer cell line and cytochromes P450. The lead compound, 21-vinyl 20-keto-pregnene (2f) (IC50 = 2.4 µM), was shown to be a promising candidate for future anticancer drug design, particularly against estrogen receptor α (ERα)-positive breast cancer. The lead compound was found to have a significant effect on the signaling pathways in parental and 4-hydroxytamoxifen-resistant cells. Compound 2f modulated the ERK, cyclin D1, and CDK4 pathways and blocked the expression of ERα, the main driver of breast cancer growth. Compound 2f significantly reduced 17β-estradiol-induced progesterone receptor expression. Accumulation of cleaved poly(ADP-ribose) polymerase in cells treated with compound 2f indicated induction of apoptosis. The selectivity analysis showed that lead compound 2f produces no significant effects on cytochromes P450, CYP19A1, CYP21A2, and CYP7B1.

A method based on the use of difluoroboron complexes was developed for the introduction of aminopyrimidinyl substituents into the side chain of ring A in (13α)-estrones.

An efficient synthetic approach based on the chelate methodology and difluoroboron complexes was developed for estrone derivatives containing pyrazolo[1,5-a]pyrimidine substituents at the side chain of ring A.

A preparation method for steroid-based difluoroboron complexes has been developed using lumiestrone as a steroid example. Previously inaccessible lumiestrone-based difluoroboron complexes annulated at positions 16 and 17 of the D ring have been prepared. Such difluoroboron complexes may have large synthetic potential for heterofunctionalization of steroids at the D ring. An application of a borylation mixture Ac2O-BF3⋅OEt2 significantly simplify the preparation of steroid "dimers" bearing two estrone moieties connected at positions 2 and 2' via a linker. Crystal structures of key representatives have been determined by X-ray diffraction.